Magnetic device for circuit control



Dec. 28, 1965 ANGR|sAN[ 3,226,506

MAGNETIC DEVICE FOR CIRCUIT CONTROL Filed June 20, 1963 FIGI FIGZ MW '5 Mi '5 H" 50 n N INVENTOR.

. yr ALDO ANGRISANI A TTORNEY United States Patent 3,226,506 MAGNETIC DEVICE FOR CIRCUIT CONTROL Aldo Angrisani, Caripito, Estado Monagas, Venezuela (Calle el Mirador-Quinta Victoria, Prados del Este- Caracas, Venezuela) Filed June 20, 1963, Ser. No. 289,372 Claims. (Cl. 200-87) 2 This invention is a novel magnetic device for control of an electric circuit. The device is appropriate for use with any one of a number of systems. For example, the device is of use in controlling a burglar alarm, and may be attached to the hood of an automobile to signal unauthorized opening of the hood.

Essentially the device comprises a magnetically actuatable switch and a stationary magnet, the flux of which may be affected by either of two mechanical inputs. At least one of these mechanical inputs is sufiicient to divert a major portion or all of the magnetic flux of the magnet from its normal direction to a path through this first input. The second input may also be effective to divert magnetic flux to the same extent as the first input or may be sufficient only to weaken and nullify the effect of the flux.

In its simplest embodiment the device of this invention can be an operator for a magnetically actuated electric switch, the two inputs serving to prevent actuation of the switch; this embodiment effectively may function as a burglar alarm. In this embodiment the device comprises a stationary magnet placed adjacent to an electric switch designed to complete a circuit under the influence of magnetic flux. The device provides, between the magnet and switch a removable ferromagnetic shield which is the first mechanical input described above. When the shield is in place between the magnet and the switch it is suflicient to divert all the magnetic flux through itself, thus preventing actuation of the switch. The shield may be fastened, for example, to the hood of an automobile so that when the hood is closed the shield is in place and the switch circuit is open. When the hood is opened, the .shield is removed from position and, unless provisions are otherwise made, the switch can close the circuit which may be attached to an alarm or signalling device, such as the automobile horn. Thus the unauthorized opening of the automobile hood will sound an alarm.

The second input in this embodiment of the device is a ferromagnetic strip between the poles of the U-shaped magnet. When this strip is perpendicular to the lines of magnetic flux between the north and south poles of the magnet it is of little or no effect on the flux. When, however, the strip is twisted to a position parallel to the flux, it absorbs an amount of the flux suflicient to prevent the magnet from actuating the switch. Thus, when opening the automobile hood, the twisting of the strip, which may be, for example, a steel key, serves to disarm the magnet allowing lifting of the hood and removal of the shield without setting olf the alarm.

The invention will be better understood by reference to the accompanying drawing in which:

FIGURE 1 is a sketch illustrative of the operation of the device with the switch open due to the positioning of the secondary strip;

FIGURE 2 is a sketch illustrative of the operation of the device with the switch closed;

FIGURE 3 is a side view of the device partly cut away and with the cover plate removed; and

FIGURE 4 is a cross-sectional view along the lines 4-4 of FIGURE 3.

The device consists of the magnetically actuatable switch indicated generally as 11, the permanent, station- 3,226,506 Patented Dec. 28, 1965 ary magnet 13, the primary shield 15 and the secondary strip 18.

The switch 11 may be more or less conventional in design. In the drawings this switch comprises the contact point 20 attached to the ferromagnetic member 22 which ideally is made of spring steel so that it may be spring biased toward the position shown in FIGURE 1 but is susceptible, under the influence of the magnet 13, to being drawn to the closed position of FIGURE 2 where contact point 20 meets the other contact point 25. The contact points are suitably joined to electrical leads 28 which are connected to a power source and a load, for example, an audible and/or visible signalling device.

The strip 18 is of flattened configuration and is made of a ferromagnetic material. It may be a key, as shown, or be actuatable by a key. The strip suitably may operate within the cylindrical core 30. The strip is of a sufllcient width that when twisted to the position shown in FIGURE 1 it will be sufiicient to absorb a fair proportion of the flux emanating from the magnet 13, but of a thickness insuflicient to absorb a significant amount of the flux in the position of FIGURE 2 or 3. When the strip 18 is twisted, the core 30 is usually twisted simultaneously.

The shield 15 is made of ferromagnetic material and may be operated by the rod 33 which rod may be suitably forked at its lower end 36 to receive the shield 15. The rod 33 may be biased by the spring 39 to put the shield 15 in the upward or non-interfering position shown in FIGURES l and 2. As is apparent from the drawing, the essential parts of the device may be enclosed within the housing 42 into which may be machined the slot 44 to serve as a guide for the shield 15 and to prevent its lateral motion under the influence of flux from the mag net 13. The device also may suitably be provided with the screw mechanism 46 adjacent the magnet 13 and the screw mechanism 48 adjacent the switch 11 for adjustment of the magnet and switch in relation to the shield 15.

As can be readily understood, while the spring 22, the shield 15, and the strip 18 are made of ferromagnetic materials and the magnet 13 is, of course, magnetized, the other materials making up the device will be of diamagnetic material such as aluminum or synthetic resins, so as not to interfere with operation of the device. Of course, the spring 39 is generally so far away from the magnet 13 that its construction from steel will not interfere.

The operation of the device is apparent from the drawings and descriptions. The device may be attached to an automobile in such a position that the closing of the hood pushes the rod 33 and shield 15 down. The electrical leads 28 are connected to make a circuit between the battery and horn of the automobile, but, with the shield 15 in the groove 44, magnetic flux from magnet 13 is prevented from reaching and actuating the switch. If, by opening the hood, the pressure of spring 39 causes movement of the shield 15 upward to the position of FIGURE 2, magnetic flux will reach spring 22 and pull contact point 20, against the biasing of the spring, to the point 25. This completes an electric circuit thereby causing the horn to sound. If, however, the strip 18 is twisted to the vertical position of FIGURE 1 before the shield 15 is raised, a good portion of the magnetic flux will pass through the strip 18 leaving the remaining flux too weak to overcome the bias of the spring 22 to close the circuit. Thus, the insertion and twisting of a key before opening the hood averts sounding of the burglar alarm. It is often desirable to have the magnetic flux diverting ability of the strip 18 strictly limited. In this way strip or secondary input 18 may be effective to hold the flux pattern established by the primary input or shield 15-while not being suflicient, in itself, to reestablish the pattern once it has been broken. Thus, twisting of the strip 18 from the horizontal, FIGURE 2 position when the shield 15 is raised, will not serve to turn off the alarm once it has sounded.

It will be understood that the operative elements of the device of this invention may be provided with a sufiicient number of mechanical accessories of sufficient size to provide any degree of remoteness desired in the operation. For example, the strip 18 may, as illustrated, be the very key which twists the core 30. Alternatively, the core 30 may be provided with a permanent strip and be turned by operation of a servo motor from a remote switch, for example, at the dashboard of the car. Likewise, the shield 15 maybe replaced by a blade which is rotatable, for example, by a spring motor. The closed hood or other closeddoor can be the damper for the spring motor and keep the blade in shielding position. Then, opening of the hood without previous twisting of the strip leads to continuous rotation of the blade, giving an intermittent or pulsing signal. Such a signal may often be preferable to indicate that the signal is not merely stuck due to a mechanical or electrical defect in the mechanism. Other variations of the accoutrernents of the novel circuit-controlling device of this invention will be obvious to ordinary skill in the art. Likewise, other types ofswitch actuatable by magnetic flux may be employed.

It is claimed:

1. A circuit-controlling device comprising a switch actuatable to a first position by establishment of a first magnetic flux pattern and biased to a second position in the absence of magnetic flux, a permanent magnet adjacent to the switch in a relationship to establish said first magnetic flux pattern, a primary ferromagnetic input means comprising an element movable from a position of non-interference with said first flux pattern to a position wherein said flux pattern is broken and a second flux pattern is established, said second flux pattern being ineffective to move said switch, and a secondary ferromagnetic input means between the poles of the magnet movable from a position aligned with said second flux pattern to a position non-aligned with said pattern, said secondary input means having a size sufficient to hold said second flux pattern when in the aligned position but insufiicient to interfere with said first flux pattern.

2. The device of claim 1 in which the first switch position is the closed position and the second switch position is the open position.

3. The device of claim 1 in which the secondary input is a strip which changes position by being twisted.

4. The device of claim 3 in which the strip is a key.

5. The device of claim 1 in which the primary input is a shield which changes position by linear displacement.

References Cited by the Examiner UNITED STATES PATENTS 1,891,568 12/1932 Morris et a1. 20087 2,767,278 10/1956 Collins -a 20087 2,924,682 2/1960 Winterburn 20087 3,005,885 10/1961 Bowditch et a1. 200 3,022,398 2/1962 Abel 20087 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. A CIRCUIT-CONTROLLING DEVICE COMPRISING A SWITCH ACTUATABLE TO A FIRST POSITION BY ESTABLISHMENT OF A FIRST MAGNETIC FLUX PATTERN AND BIASED TO A SECOND POSITION IN THE ABSENCE OF MAGNETIC FLUX, A PERMANENT MAGNET ADJACENT TO THE SWITCH IN A RELATIONSHIP TO ESTABLISH SAID FIRST MAGNETIC FLUX PATTERN, A PRIMARY FERROMAGNETIC INPUT MEANS COMPRISING AN ELEMENT MOVABLE FROM A POSITION OF NON-INTERFERENCE WITH SAID FIRST FLUX PATTERN TO A POSITION WHEREIN SAID FLUX PATTERN IS BROKEN AND A SECOND FLUX PATTERN IS ESTABLISHED, SAID SECOND FLUX PATTERN BEING INEFFECTIVE TO MOVE SAID SWITCH, AND A SECONDARY FERROMAGNETIC INPUT MEANS BETWEEN THE POLES OF THE MAGNET MOVABLE FROM A POSITION ALIGNED WITH SAID SECOND FLUX PATTERN TO A POSITION NON-ALIGNED WITH SAID PATTERN, SAID SEONDARY INPUT MEANS HAVING A SIZE SUFFICIENT TO HOLE SAID SECOND FLUX PATTERN WHEN IT THE ALIGNED POSITION BUT INSUFFICIENT TO INTERFERE WITH SAID FIRST FLUX PATTERN. 